MYIB/HONORS PHYSICS NAME:
PROBLEM SET: Electric Charge and Electric Fields
Solve the following problems on a separate sheet of paper. Correct answers are at the end of the problem set.
A. The Fundamental Charge / Conservation of Charge
1. (I) What is the net charge of an electron?
2. (I) If a particle gained 1.2 x 107 electrons, what is the charge on the particle?
3. (I) If a particle loses 1.5 x 104 electrons, what is the charge on the particle?
4. (I) If a particle has a charge of +45 mC, has it gained or lost electrons? How many electrons has it gained or lost?
5. (I) If sphere A has a charge of +5 mC and sphere B has a charge of +2 mC, what is the charge on each sphere after A is touched to B and then removed?
6. (I) Sphere A has 4.5 x 104 extra electrons. It is brought into contact with sphere B, which has 3.5 x 104 electrons missing. After the contact what is the charge on each sphere?
7. (I) A small pith ball carries a charge of –2.5 x 10-6 C. How many excess electrons does this charge represent?
1) −1.6 × 10−19 C / 2) −1.92 × 10−12 C / 3) +2.4 × 10−15 C / 4) lost 2.81 × 1014 / 5) +3.5 mC / 6) −8.0 × 10−16 C7) 1.56 × 1013
B. Coulomb’s Law / Electrostatic Force / Electric Fields
1. (I) A positive force calculated from Coulomb’s Law indicates ______.
2. (I) A negative force calculated from Coulomb’s Law indicates ______.
3. (II) Two identical positive charges are moved twice as far apart from each other. How will the new force of repulsion compare to the original force?
4. (II) Two charges are move three times closer to each other. How will the force between them change?
5. (I) Two positive charges of 6.0 x 10−6 C are 0.30 m apart. What force exists between the two charges?
6. (II) A force of 90.0 N exists between a +15 mC charge and a −15 mC charge. How far apart are the charges?
7. (II) A negative charge of 6.0 x 10−6 C exerts an attractive force of 64.8 N on a second charge 0.05 m away. What is the second charge?
8. (III) Determine the magnitude and direction of the net force on the middle charge shown below.
9. (III) Determine the net electrostatic force on q2 shown in the diagram below.
10. (I)What is the electric field intensity at a location of 10 cm from a +5 μC point charge? Is the field directed toward or away from the point charge?
11. (II)A test charge experiences a field intensity of 3.0 x 105 N/C when located near a −3.0 μC point charge. How far away is the point charge from the test charge?
12. (III)Two point charges are separated by 10.0 cm. One has a charge of −25 μC and is placed 10.0 cm to the left of a +50 μC charge.
a What is the magnitude and direction of the electric field at point P in between them, if P is located 2.00 cm from the negative charge?
b If an electron is placed at rest at point P, what will be its initial acceleration (magnitude and direction)?
13. (I) A positive test charge of 8.0 x 10−5 C is placed in an electric field. It experiences a force of 4.0 x 10−3 N. What is the electric field intensity at this point?
14. (II) A positive test charge of 5.0 x 10−4 C is placed in the electric field of a point charge. The test charge experiences a force of −5.0 x10−4 N (the negative indicates that the force is directed inward). What is the field intensity at the location of the test charge, and type of charge creating the electric field?
15. Draw the electric field lines for the situations below.
16. If a test charge is moved twice as far from a point charge from its original location, the field intensity the charge experiences will _____.
1) repulsion / 2) attraction / 3) ¼ as much / 4) 9 times more / 5) 3.6 N6) 15 cm / 7) +3.0 × 10−6 C / 8) 157.5 N right / 9) 130.8 N, 40.16° south of east / 10) 4.5 × 106 N/C away / 11) 0.3 m or 30 cm
12) a. 6.328 × 108 N/C; left
b. 1.111 × 1020 m/s2; right / 13) 50 N/C / 14) 1 N/C; negative / 15) See Instructor / 16) be ¼ of the original intensity